System, apparatus and method for sensor-driven and heuristic-based minimum energy point tracking in a processor

ABSTRACT

In one embodiment, a processor includes a minimum energy point (MEP) controller to: generate a change in thermal tracking information, based at least in part on prior and current thermal information; generate a change in activity tracking information, based at least in part on prior activity information and current activity information; and determine a MEP performance state based at least in part on the change in thermal tracking information and the change in activity tracking information. Other embodiments are described and claimed.

TECHNICAL FIELD

Embodiments relate to controlling power to digital integrated circuitsto reduce energy consumption under various conditions.

BACKGROUND

Energy consumption in most digital integrated circuits is highlydependent on the supply voltage that powers the integrated circuits andon the frequency of the clock that controls the switching of theintegrated circuits. Today's integrated circuits are able to operateover a wide dynamic range of both supply voltage and frequency, whichcan result in a widely varying range of energy efficiencies. Inparticular, the best energy efficiencies in digital CMOS silicon may beachieved around the “near-threshold voltage” (NTV) regime with anoptimum supply voltage and frequency and a distinct minimum energy point(MEP), where energy efficiencies can be 5-10× better than nominal supplyoperation. The optimum voltage and MEP can vary widely across workloadactivity and with process and temperature variations. Non-linearintegrated voltage regulator (IVR) efficiencies can further shift MEPand optimum voltage, as the energy consumed by the entire system istaken into account. Finding a truly optimal MEP can make a significantdifference in the energy consumed by the system. Current techniques failto do so in an efficient manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a portion of a system in accordance with anembodiment of the present invention.

FIG. 2 is a block diagram of a processor in accordance with anembodiment of the present invention.

FIG. 3 is a block diagram of a multi-domain processor in accordance withanother embodiment of the present invention.

FIG. 4 is an embodiment of a processor including multiple cores.

FIG. 5 is a block diagram of a micro-architecture of a processor core inaccordance with one embodiment of the present invention.

FIG. 6 is a block diagram of a micro-architecture of a processor core inaccordance with another embodiment.

FIG. 7 is a block diagram of a micro-architecture of a processor core inaccordance with yet another embodiment.

FIG. 8 is a block diagram of a micro-architecture of a processor core inaccordance with a still further embodiment.

FIG. 9 is a block diagram of a processor in accordance with anotherembodiment of the present invention.

FIG. 10 is a block diagram of a representative SoC in accordance with anembodiment of the present invention.

FIG. 11 is a block diagram of another example SoC in accordance with anembodiment of the present invention.

FIG. 12 is a block diagram of an example system with which embodimentscan be used.

FIG. 13 is a block diagram of another example system with whichembodiments may be used.

FIG. 14 is a block diagram of a representative computer system.

FIG. 15 is a block diagram of a system in accordance with an embodimentof the present invention.

FIG. 16 is a block diagram illustrating an IP core development systemused to manufacture an integrated circuit to perform operationsaccording to an embodiment.

FIG. 17 is a flow diagram of a method in accordance with an embodimentof the present invention.

FIG. 18 is a flow diagram of a method in accordance with anotherembodiment of the present invention.

FIG. 19 is a graphical illustration of energy consumption with relationto operating voltage in accordance with an embodiment of the presentinvention.

FIG. 20 is a set of representative simulated MEP curves for changes inworkload activity in accordance with an embodiment of the presentinvention.

FIG. 21 is an example illustration of change in MEP versus temperatureand activity in accordance with an embodiment of the present invention.

FIG. 22 is a block diagram of a MEP controller in accordance with anembodiment of the present invention.

FIG. 23 is a block diagram of a MEP controller in accordance withanother embodiment of the present invention.

DETAILED DESCRIPTION

In various embodiments, a processor is configured with a minimum energypoint (MEP) control circuit to determine and track a MEP of theprocessor and/or its constituent components, including one or more coresor other processing circuits. To enable efficient tracking of MEP over alifetime of the processor at high speed and low impact, embodimentsleverage an efficient sensor-driven energy computation technique toarrive at the MEP. As such, embodiments may determine and track MEP forthe processor with high speed and low complexity, in contrast toconventional one point (at a time) sweep-based energy computing methods,which perform many update iterations to processor operating voltage andoperating frequency, in an effort to identify an MEP for a givenworkload.

With embodiments herein, sensor-driven and heuristic techniques providefast real-time MEP tracking, resulting in simplifiedrelative-computational computations, with reduced overhead. As a result,embodiments may realize better MEP tracking, as the techniques hereinenable a determination of an updated MEP point substantially faster ascompared to a recursive/expensive search, when operating conditions of aprocessor change. Stated another way, a conventional (e.g., dynamicvoltage frequency scaling (DVFS)) technique to identify a MEP, withmultiple voltage and frequency updates, can be replaced in embodimentswith intelligent and direct computational hardware to predict MEP andupdate operation directly to this operating point in a single step,improving performance.

In embodiments, a MEP controller may leverage sensor-driven data andheuristics to quickly compute and relock to a new optimal MEP point,using one or more pre-characterized (and per-die programmable) lookuptables (LUTs). With embodiments, the MEP may be determined in a relativemanner as compared to a computationally expensive absolute MEP trackingmethod to intelligently adjust an optimum MEP.

Although the following embodiments are described with reference toenergy conservation and energy efficiency in specific integratedcircuits, such as in computing platforms or processors, otherembodiments are applicable to other types of integrated circuits andlogic devices. Similar techniques and teachings of embodiments describedherein may be applied to other types of circuits or semiconductordevices that may also benefit from better energy efficiency and energyconservation. For example, the disclosed embodiments are not limited toany particular type of computer systems. That is, disclosed embodimentscan be used in many different system types, ranging from servercomputers (e.g., tower, rack, blade, micro-server and so forth),communications systems, storage systems, desktop computers of anyconfiguration, laptop, notebook, and tablet computers (including 2:1tablets, phablets and so forth), and may be also used in other devices,such as handheld devices, systems on chip (SoCs), and embeddedapplications. Some examples of handheld devices include cellular phonessuch as smartphones, Internet protocol devices, digital cameras,personal digital assistants (PDAs), and handheld PCs. Embeddedapplications may typically include a microcontroller, a digital signalprocessor (DSP), network computers (NetPC), set-top boxes, network hubs,wide area network (WAN) switches, wearable devices, or any other systemthat can perform the functions and operations taught below. More so,embodiments may be implemented in mobile terminals having standard voicefunctionality such as mobile phones, smartphones and phablets, and/or innon-mobile terminals without a standard wireless voice functioncommunication capability, such as many wearables, tablets, notebooks,desktops, micro-servers, servers and so forth. Moreover, theapparatuses, methods, and systems described herein are not limited tophysical computing devices, but may also relate to softwareoptimizations for energy conservation and efficiency. As will becomereadily apparent in the description below, the embodiments of methods,apparatuses, and systems described herein (whether in reference tohardware, firmware, software, or a combination thereof) are vital to a‘green technology’ future, such as for power conservation and energyefficiency in products that encompass a large portion of the US economy.

Referring now to FIG. 1, shown is a block diagram of a portion of asystem in accordance with an embodiment of the present invention. Asshown in FIG. 1, system 100 may include various components, including aprocessor 110 which as shown is a multicore processor. Processor 110 maybe coupled to a power supply 150 via an external voltage regulator 160,which may perform a first voltage conversion to provide a primaryregulated voltage to processor 110.

As seen, processor 110 may be a single die processor including multiplecores 120 _(a)-120 _(n). In addition, each core may be associated withan integrated voltage regulator (IVR) 125 _(a)-125 _(n) which receivesthe primary regulated voltage and generates an operating voltage to beprovided to one or more agents of the processor associated with the IVR.Accordingly, an IVR implementation may be provided to allow forfine-grained control of voltage and thus power and performance of eachindividual core. As such, each core can operate at an independentvoltage and frequency, enabling great flexibility and affording wideopportunities for balancing power consumption with performance. In someembodiments, the use of multiple IVRs enables the grouping of componentsinto separate power planes, such that power is regulated and supplied bythe IVR to only those components in the group. During power management,a given power plane of one IVR may be powered down or off when theprocessor is placed into a certain low power state, while another powerplane of another IVR remains active, or fully powered.

Still referring to FIG. 1, additional components may be present withinthe processor including an input/output interface 132, another interface134, and an integrated memory controller 136. As seen, each of thesecomponents may be powered by another integrated voltage regulator 125_(χ). In one embodiment, interface 132 may be enable operation for anIntel®. Quick Path Interconnect (QPI) interconnect, which provides forpoint-to-point (PtP) links in a cache coherent protocol that includesmultiple layers including a physical layer, a link layer and a protocollayer. In turn, interface 134 may communicate via a Peripheral ComponentInterconnect Express (PCIe™) protocol.

Also shown is a power control unit (PCU) 138, which may includehardware, software and/or firmware to perform power managementoperations with regard to processor 110. As seen, PCU 138 providescontrol information to external voltage regulator 160 via a digitalinterface to cause the voltage regulator to generate the appropriateregulated voltage. PCU 138 also provides control information to IVRs 125via another digital interface to control the operating voltage generated(or to cause a corresponding IVR to be disabled in a low power mode). Invarious embodiments, PCU 138 may include a variety of power managementlogic units to perform hardware-based power management. Such powermanagement may be wholly processor controlled (e.g., by variousprocessor hardware, and which may be triggered by workload and/or power,thermal or other processor constraints) and/or the power management maybe performed responsive to external sources (such as a platform ormanagement power management source or system software).

Furthermore, while FIG. 1 shows an implementation in which PCU 138 is aseparate processing engine (which may be implemented as amicrocontroller), understand that in some cases in addition to orinstead of a dedicated power controller, each core may include or beassociated with a power control agent to more autonomously control powerconsumption independently. In some cases a hierarchical power managementarchitecture may be provided, with PCU 138 in communication withcorresponding power management agents associated with each of cores 120.

One power management logic included in PCU 138 may be a MEP controllerthat is configured to readily and efficiently identify a MEP operatingpoint based at least in part on dynamic processor conditions includingchanges in thermal information and/or activity information. Stillfurther, the MEP controller may determine an initial MEP operating pointbased at least in part on a sweep of a plurality of operating voltageand operating frequency points and a process variation of the processor.Thereafter, the MEP controller may identify an appropriate update to theMEP operating point based at least in part on one or more of activitytracking information and temperature tracking information, as describedherein.

While not shown for ease of illustration, understand that additionalcomponents may be present within processor 110 such as additionalcontrol circuitry, and other components such as internal memories, e.g.,one or more levels of a cache memory hierarchy and so forth.Furthermore, while shown in the implementation of FIG. 1 with anintegrated voltage regulator, embodiments are not so limited.

Note that the power management techniques described herein may beindependent of and complementary to an operating system (OS)-based powermanagement (OSPM) mechanism. According to one example OSPM technique, aprocessor can operate at various performance states or levels, so-calledP-states, namely from P0 to PN. In general, the P1 performance state maycorrespond to the highest guaranteed performance state that can berequested by an OS. Embodiments described herein may enable dynamicchanges to the guaranteed frequency of the P1 performance state, basedon a variety of inputs and processor operating parameters. In additionto this P1 state, the OS can further request a higher performance state,namely a P0 state. This P0 state may thus be an opportunistic or turbomode state in which, when power and/or thermal budget is available,processor hardware can configure the processor or at least portionsthereof to operate at a higher than guaranteed frequency. In manyimplementations a processor can include multiple so-called binfrequencies above the P1 guaranteed maximum frequency, exceeding to amaximum peak frequency of the particular processor, as fused orotherwise written into the processor during manufacture. In addition,according to one OSPM mechanism, a processor can operate at variouspower states or levels. With regard to power states, an OSPM mechanismmay specify different power consumption states, generally referred to asC-states, C0, C1 to Cn states. When a core is active, it runs at a C0state, and when the core is idle it may be placed in a core low powerstate, also called a core non-zero C-state (e.g., C1-C6 states), witheach C-state being at a lower power consumption level (such that C6 is adeeper low power state than C1, and so forth).

Understand that many different types of power management techniques maybe used individually or in combination in different embodiments. Asrepresentative examples, a power controller may control the processor tobe power managed by some form of dynamic voltage frequency scaling(DVFS) in which an operating voltage and/or operating frequency of oneor more cores or other processor logic may be dynamically controlled toreduce power consumption in certain situations. In an example, DVFS maybe performed using Enhanced Intel SpeedStep™ technology available fromIntel Corporation, Santa Clara, Calif., to provide optimal performanceat a lowest power consumption level. In another example, DVFS may beperformed using Intel TurboBoost™ technology to enable one or more coresor other compute engines to operate at a higher than guaranteedoperating frequency based on conditions (e.g., workload andavailability).

Another power management technique that may be used in certain examplesis dynamic swapping of workloads between different compute engines. Forexample, the processor may include asymmetric cores or other processingengines that operate at different power consumption levels, such that ina power constrained situation, one or more workloads can be dynamicallyswitched to execute on a lower power core or other compute engine.Another exemplary power management technique is hardware duty cycling(HDC), which may cause cores and/or other compute engines to beperiodically enabled and disabled according to a duty cycle, such thatone or more cores may be made inactive during an inactive period of theduty cycle and made active during an active period of the duty cycle.Although described with these particular examples, understand that manyother power management techniques may be used in particular embodiments.

Embodiments can be implemented in processors for various marketsincluding server processors, desktop processors, mobile processors andso forth. Referring now to FIG. 2, shown is a block diagram of aprocessor in accordance with an embodiment of the present invention. Asshown in FIG. 2, processor 200 may be a multicore processor including aplurality of cores 210 _(a)-210 _(n). In one embodiment, each such coremay be of an independent power domain and can be configured to enter andexit active states and/or maximum performance states based on workload.The various cores may be coupled via an interconnect 215 to a systemagent 220 that includes various components. As seen, system agent 220may include a shared cache 230 which may be a last level cache. Inaddition, the system agent may include an integrated memory controller240 to communicate with a system memory (not shown in FIG. 2), e.g., viaa memory bus. System agent 220 also includes various interfaces 250 anda power control unit 255, which may include logic to perform the powermanagement techniques described herein. In the embodiment shown, powercontrol unit 255 includes a MEP controller 258 that may determine aninitial MEP point for processor 200. In addition, MEP controller 258 maydynamically determine one or more updates to the MEP operating pointbased at least in part on activity tracking information and/ortemperature tracking information as described herein. In addition, atappropriate age-related time durations, MEP controller 258 may determinean updated optimum MEP performance state.

In addition, by interfaces 250 a-250 n, connection can be made tovarious off-chip components such as peripheral devices, mass storage andso forth. While shown with this particular implementation in theembodiment of FIG. 2, the scope of the present invention is not limitedin this regard.

Referring now to FIG. 3, shown is a block diagram of a multi-domainprocessor in accordance with another embodiment of the presentinvention. As shown in the embodiment of FIG. 3, processor 300 includesmultiple domains. Specifically, a core domain 310 can include aplurality of cores 310 ₀-310 _(n), a graphics domain 320 can include oneor more graphics engines, and a system agent domain 350 may further bepresent. In some embodiments, system agent domain 350 may execute at anindependent frequency than the core domain and may remain powered on atall times to handle power control events and power management such thatdomains 310 and 320 can be controlled to dynamically enter into and exithigh power and low power states. Each of domains 310 and 320 may operateat different voltage and/or power. Note that while only shown with threedomains, understand the scope of the present invention is not limited inthis regard and additional domains can be present in other embodiments.For example, multiple core domains may be present each including atleast one core.

In general, each core 310 may further include low level caches inaddition to various execution units and additional processing elements.In turn, the various cores may be coupled to each other and to a sharedcache memory formed of a plurality of units of a last level cache (LLC)340 ₀-340 _(n). In various embodiments, LLC 340 may be shared amongstthe cores and the graphics engine, as well as various media processingcircuitry. As seen, a ring interconnect 330 thus couples the corestogether, and provides interconnection between the cores, graphicsdomain 320 and system agent circuitry 350. In one embodiment,interconnect 330 can be part of the core domain. However in otherembodiments the ring interconnect can be of its own domain.

As further seen, system agent domain 350 may include display controller352 which may provide control of and an interface to an associateddisplay. As further seen, system agent domain 350 may include a powercontrol unit 355 which can include logic to perform the power managementtechniques described herein. In the embodiment shown, power control unit355 includes a MEP controller 359, which may determine initial andupdated MEP operating points based on some or all of process variationinformation, activity tracking information and temperature trackinginformation, using a heuristic-based approach to leverage information inone or more lookup tables, as described herein.

As further seen in FIG. 3, processor 300 can further include anintegrated memory controller (IMC) 370 that can provide for an interfaceto a system memory, such as a dynamic random access memory (DRAM).Multiple interfaces 380 ₀-380 _(n) may be present to enableinterconnection between the processor and other circuitry. For example,in one embodiment at least one direct media interface (DMI) interfacemay be provided as well as one or more PCIe™ interfaces. Still further,to provide for communications between other agents such as additionalprocessors or other circuitry, one or more QPI interfaces may also beprovided. Although shown at this high level in the embodiment of FIG. 3,understand the scope of the present invention is not limited in thisregard.

Referring to FIG. 4, an embodiment of a processor including multiplecores is illustrated. Processor 400 includes any processor or processingdevice, such as a microprocessor, an embedded processor, a digitalsignal processor (DSP), a network processor, a handheld processor, anapplication processor, a co-processor, a system on a chip (SoC), orother device to execute code. Processor 400, in one embodiment, includesat least two cores—cores 401 and 402, which may include asymmetric coresor symmetric cores (the illustrated embodiment). However, processor 400may include any number of processing elements that may be symmetric orasymmetric.

In one embodiment, a processing element refers to hardware or logic tosupport a software thread. Examples of hardware processing elementsinclude: a thread unit, a thread slot, a thread, a process unit, acontext, a context unit, a logical processor, a hardware thread, a core,and/or any other element, which is capable of holding a state for aprocessor, such as an execution state or architectural state. In otherwords, a processing element, in one embodiment, refers to any hardwarecapable of being independently associated with code, such as a softwarethread, operating system, application, or other code. A physicalprocessor typically refers to an integrated circuit, which potentiallyincludes any number of other processing elements, such as cores orhardware threads.

A core often refers to logic located on an integrated circuit capable ofmaintaining an independent architectural state, wherein eachindependently maintained architectural state is associated with at leastsome dedicated execution resources. In contrast to cores, a hardwarethread typically refers to any logic located on an integrated circuitcapable of maintaining an independent architectural state, wherein theindependently maintained architectural states share access to executionresources. As can be seen, when certain resources are shared and othersare dedicated to an architectural state, the line between thenomenclature of a hardware thread and core overlaps. Yet often, a coreand a hardware thread are viewed by an operating system as individuallogical processors, where the operating system is able to individuallyschedule operations on each logical processor.

Physical processor 400, as illustrated in FIG. 4, includes two cores,cores 401 and 402. Here, cores 401 and 402 are considered symmetriccores, i.e., cores with the same configurations, functional units,and/or logic. In another embodiment, core 401 includes an out-of-orderprocessor core, while core 402 includes an in-order processor core.However, cores 401 and 402 may be individually selected from any type ofcore, such as a native core, a software managed core, a core adapted toexecute a native instruction set architecture (ISA), a core adapted toexecute a translated ISA, a co-designed core, or other known core. Yetto further the discussion, the functional units illustrated in core 401are described in further detail below, as the units in core 402 operatein a similar manner.

As depicted, core 401 includes two hardware threads 401 a and 401 b,which may also be referred to as hardware thread slots 401 a and 401 b.Therefore, software entities, such as an operating system, in oneembodiment potentially view processor 400 as four separate processors,i.e., four logical processors or processing elements capable ofexecuting four software threads concurrently. As alluded to above, afirst thread is associated with architecture state registers 401 a, asecond thread is associated with architecture state registers 401 b, athird thread may be associated with architecture state registers 402 a,and a fourth thread may be associated with architecture state registers402 b. Here, each of the architecture state registers (401 a, 401 b, 402a, and 402 b) may be referred to as processing elements, thread slots,or thread units, as described above. As illustrated, architecture stateregisters 401 a are replicated in architecture state registers 401 b, soindividual architecture states/contexts are capable of being stored forlogical processor 401 a and logical processor 401 b. In core 401, othersmaller resources, such as instruction pointers and renaming logic inallocator and renamer block 430 may also be replicated for threads 401 aand 401 b. Some resources, such as re-order buffers inreorder/retirement unit 435, ILTB 420, load/store buffers, and queuesmay be shared through partitioning. Other resources, such as generalpurpose internal registers, page-table base register(s), low-leveldata-cache and data-TLB 415, execution unit(s) 440, and portions ofout-of-order unit 435 are potentially fully shared.

Processor 400 often includes other resources, which may be fully shared,shared through partitioning, or dedicated by/to processing elements. InFIG. 4, an embodiment of a purely exemplary processor with illustrativelogical units/resources of a processor is illustrated. Note that aprocessor may include, or omit, any of these functional units, as wellas include any other known functional units, logic, or firmware notdepicted. As illustrated, core 401 includes a simplified, representativeout-of-order (OOO) processor core. But an in-order processor may beutilized in different embodiments. The OOO core includes a branch targetbuffer 420 to predict branches to be executed/taken and aninstruction-translation buffer (I-TLB) 420 to store address translationentries for instructions.

Core 401 further includes decode module 425 coupled to fetch unit 420 todecode fetched elements. Fetch logic, in one embodiment, includesindividual sequencers associated with thread slots 401 a, 401 b,respectively. Usually core 401 is associated with a first ISA, whichdefines/specifies instructions executable on processor 400. Oftenmachine code instructions that are part of the first ISA include aportion of the instruction (referred to as an opcode), whichreferences/specifies an instruction or operation to be performed. Decodelogic 425 includes circuitry that recognizes these instructions fromtheir opcodes and passes the decoded instructions on in the pipeline forprocessing as defined by the first ISA. For example, decoders 425, inone embodiment, include logic designed or adapted to recognize specificinstructions, such as transactional instruction. As a result of therecognition by decoders 425, the architecture or core 401 takesspecific, predefined actions to perform tasks associated with theappropriate instruction. It is important to note that any of the tasks,blocks, operations, and methods described herein may be performed inresponse to a single or multiple instructions; some of which may be newor old instructions.

In one example, allocator and renamer block 430 includes an allocator toreserve resources, such as register files to store instructionprocessing results. However, threads 401 a and 401 b are potentiallycapable of out-of-order execution, where allocator and renamer block 430also reserves other resources, such as reorder buffers to trackinstruction results. Unit 430 may also include a register renamer torename program/instruction reference registers to other registersinternal to processor 400. Reorder/retirement unit 435 includescomponents, such as the reorder buffers mentioned above, load buffers,and store buffers, to support out-of-order execution and later in-orderretirement of instructions executed out-of-order.

Scheduler and execution unit(s) block 440, in one embodiment, includes ascheduler unit to schedule instructions/operation on execution units.For example, a floating point instruction is scheduled on a port of anexecution unit that has an available floating point execution unit.Register files associated with the execution units are also included tostore information instruction processing results. Exemplary executionunits include a floating point execution unit, an integer executionunit, a jump execution unit, a load execution unit, a store executionunit, and other known execution units.

Lower level data cache and data translation buffer (D-TLB) 450 arecoupled to execution unit(s) 440. The data cache is to store recentlyused/operated on elements, such as data operands, which are potentiallyheld in memory coherency states. The D-TLB is to store recentvirtual/linear to physical address translations. As a specific example,a processor may include a page table structure to break physical memoryinto a plurality of virtual pages.

Here, cores 401 and 402 share access to higher-level or further-outcache 410, which is to cache recently fetched elements. Note thathigher-level or further-out refers to cache levels increasing or gettingfurther away from the execution unit(s). In one embodiment, higher-levelcache 410 is a last-level data cache—last cache in the memory hierarchyon processor 400—such as a second or third level data cache. However,higher level cache 410 is not so limited, as it may be associated withor includes an instruction cache. A trace cache—a type of instructioncache—instead may be coupled after decoder 425 to store recently decodedtraces.

In the depicted configuration, processor 400 also includes bus interfacemodule 405 and a power controller 460, which may perform powermanagement in accordance with an embodiment of the present invention. Inthis scenario, bus interface 405 is to communicate with devices externalto processor 400, such as system memory and other components.

A memory controller 470 may interface with other devices such as one ormany memories. In an example, bus interface 405 includes a ringinterconnect with a memory controller for interfacing with a memory anda graphics controller for interfacing with a graphics processor. In anSoC environment, even more devices, such as a network interface,coprocessors, memory, graphics processor, and any other known computerdevices/interface may be integrated on a single die or integratedcircuit to provide small form factor with high functionality and lowpower consumption.

Referring now to FIG. 5, shown is a block diagram of amicro-architecture of a processor core in accordance with one embodimentof the present invention. As shown in FIG. 5, processor core 500 may bea multi-stage pipelined out-of-order processor. Core 500 may operate atvarious voltages based on a received operating voltage, which may bereceived from an integrated voltage regulator or external voltageregulator.

As seen in FIG. 5, core 500 includes front end units 510, which may beused to fetch instructions to be executed and prepare them for use laterin the processor pipeline. For example, front end units 510 may includea fetch unit 501, an instruction cache 503, and an instruction decoder505. In some implementations, front end units 510 may further include atrace cache, along with microcode storage as well as a micro-operationstorage. Fetch unit 501 may fetch macro-instructions, e.g., from memoryor instruction cache 503, and feed them to instruction decoder 505 todecode them into primitives, i.e., micro-operations for execution by theprocessor.

Coupled between front end units 510 and execution units 520 is anout-of-order (OOO) engine 515 that may be used to receive themicro-instructions and prepare them for execution. More specifically OOOengine 515 may include various buffers to re-order micro-instructionflow and allocate various resources needed for execution, as well as toprovide renaming of logical registers onto storage locations withinvarious register files such as register file 530 and extended registerfile 535. Register file 530 may include separate register files forinteger and floating point operations. Extended register file 535 mayprovide storage for vector-sized units, e.g., 256 or 512 bits perregister. For purposes of configuration, control, and additionaloperations, a set of machine specific registers (MSRs) 538 may also bepresent and accessible to various logic within core 500 (and external tothe core).

Various resources may be present in execution units 520, including, forexample, various integer, floating point, and single instructionmultiple data (SIMD) logic units, among other specialized hardware. Forexample, such execution units may include one or more arithmetic logicunits (ALUs) 522 and one or more vector execution units 524, among othersuch execution units.

Results from the execution units may be provided to retirement logic,namely a reorder buffer (ROB) 540. More specifically, ROB 540 mayinclude various arrays and logic to receive information associated withinstructions that are executed. This information is then examined by ROB540 to determine whether the instructions can be validly retired andresult data committed to the architectural state of the processor, orwhether one or more exceptions occurred that prevent a proper retirementof the instructions. Of course, ROB 540 may handle other operationsassociated with retirement.

As shown in FIG. 5, ROB 540 is coupled to a cache 550 which, in oneembodiment may be a low level cache (e.g., an L1 cache) although thescope of the present invention is not limited in this regard. Also,execution units 520 can be directly coupled to cache 550. From cache550, data communication may occur with higher level caches, systemmemory and so forth. While shown with this high level in the embodimentof FIG. 5, understand the scope of the present invention is not limitedin this regard. For example, while the implementation of FIG. 5 is withregard to an out-of-order machine such as of an Intel® x86 instructionset architecture (ISA), the scope of the present invention is notlimited in this regard. That is, other embodiments may be implemented inan in-order processor, a reduced instruction set computing (RISC)processor such as an ARM-based processor, or a processor of another typeof ISA that can emulate instructions and operations of a different ISAvia an emulation engine and associated logic circuitry.

Referring now to FIG. 6, shown is a block diagram of amicro-architecture of a processor core in accordance with anotherembodiment. In the embodiment of FIG. 6, core 600 may be a low powercore of a different micro-architecture, such as an Intel®. Atom™-basedprocessor having a relatively limited pipeline depth designed to reducepower consumption. As seen, core 600 includes an instruction cache 610coupled to provide instructions to an instruction decoder 615. A branchpredictor 605 may be coupled to instruction cache 610. Note thatinstruction cache 610 may further be coupled to another level of a cachememory, such as an L2 cache (not shown for ease of illustration in FIG.6). In turn, instruction decoder 615 provides decoded instructions to anissue queue 620 for storage and delivery to a given execution pipeline.A microcode ROM 618 is coupled to instruction decoder 615.

A floating point pipeline 630 includes a floating point register file632 which may include a plurality of architectural registers of a givenbit with such as 128, 256 or 512 bits. Pipeline 630 includes a floatingpoint scheduler 634 to schedule instructions for execution on one ofmultiple execution units of the pipeline. In the embodiment shown, suchexecution units include an ALU 635, a shuffle unit 636, and a floatingpoint adder 638. In turn, results generated in these execution units maybe provided back to buffers and/or registers of register file 632. Ofcourse understand while shown with these few example execution units,additional or different floating point execution units may be present inanother embodiment.

An integer pipeline 640 also may be provided. In the embodiment shown,pipeline 640 includes an integer register file 642 which may include aplurality of architectural registers of a given bit with such as 128 or256 bits. Pipeline 640 includes an integer scheduler 644 to scheduleinstructions for execution on one of multiple execution units of thepipeline. In the embodiment shown, such execution units include an ALU645, a shifter unit 646, and a jump execution unit 648. In turn, resultsgenerated in these execution units may be provided back to buffersand/or registers of register file 642. Of course understand while shownwith these few example execution units, additional or different integerexecution units may be present in another embodiment.

A memory execution scheduler 650 may schedule memory operations forexecution in an address generation unit 652, which is also coupled to aTLB 654. As seen, these structures may couple to a data cache 660, whichmay be a L0 and/or L1 data cache that in turn couples to additionallevels of a cache memory hierarchy, including an L2 cache memory.

To provide support for out-of-order execution, an allocator/renamer 670may be provided, in addition to a reorder buffer 680, which isconfigured to reorder instructions executed out of order for retirementin order. Although shown with this particular pipeline architecture inthe illustration of FIG. 6, understand that many variations andalternatives are possible.

Note that in a processor having asymmetric cores, such as in accordancewith the micro-architectures of FIGS. 5 and 6, workloads may bedynamically swapped between the cores for power management reasons, asthese cores, although having different pipeline designs and depths, maybe of the same or related ISA. Such dynamic core swapping may beperformed in a manner transparent to a user application (and possiblykernel also).

Referring to FIG. 7, shown is a block diagram of a micro-architecture ofa processor core in accordance with yet another embodiment. Asillustrated in FIG. 7, a core 700 may include a multi-staged in-orderpipeline to execute at very low power consumption levels. As one suchexample, processor 700 may have a micro-architecture in accordance withan ARM Cortex A53 design available from ARM Holdings, LTD., Sunnyvale,Calif. In an implementation, an 8-stage pipeline may be provided that isconfigured to execute both 32-bit and 64-bit code. Core 700 includes afetch unit 710 that is configured to fetch instructions and provide themto a decode unit 715, which may decode the instructions, e.g.,macro-instructions of a given ISA such as an ARMv8 ISA. Note furtherthat a queue 730 may couple to decode unit 715 to store decodedinstructions. Decoded instructions are provided to an issue logic 725,where the decoded instructions may be issued to a given one of multipleexecution units.

With further reference to FIG. 7, issue logic 725 may issue instructionsto one of multiple execution units. In the embodiment shown, theseexecution units include an integer unit 735, a multiply unit 740, afloating point/vector unit 750, a dual issue unit 760, and a load/storeunit 770. The results of these different execution units may be providedto a writeback unit 780. Understand that while a single writeback unitis shown for ease of illustration, in some implementations separatewriteback units may be associated with each of the execution units.Furthermore, understand that while each of the units and logic shown inFIG. 7 is represented at a high level, a particular implementation mayinclude more or different structures. A processor designed using one ormore cores having a pipeline as in FIG. 7 may be implemented in manydifferent end products, extending from mobile devices to server systems.

Referring to FIG. 8, shown is a block diagram of a micro-architecture ofa processor core in accordance with a still further embodiment. Asillustrated in FIG. 8, a core 800 may include a multi-stage multi-issueout-of-order pipeline to execute at very high performance levels (whichmay occur at higher power consumption levels than core 700 of FIG. 7).As one such example, processor 800 may have a microarchitecture inaccordance with an ARM Cortex A57 design. In an implementation, a 15 (orgreater)-stage pipeline may be provided that is configured to executeboth 32-bit and 64-bit code. In addition, the pipeline may provide for 3(or greater)-wide and 3 (or greater)-issue operation. Core 800 includesa fetch unit 810 that is configured to fetch instructions and providethem to a decoder/renamer/dispatcher 815, which may decode theinstructions, e.g., macro-instructions of an ARMv8 instruction setarchitecture, rename register references within the instructions, anddispatch the instructions (eventually) to a selected execution unit.Decoded instructions may be stored in a queue 825. Note that while asingle queue structure is shown for ease of illustration in FIG. 8,understand that separate queues may be provided for each of the multipledifferent types of execution units.

Also shown in FIG. 8 is an issue logic 830 from which decodedinstructions stored in queue 825 may be issued to a selected executionunit. Issue logic 830 also may be implemented in a particular embodimentwith a separate issue logic for each of the multiple different types ofexecution units to which issue logic 830 couples.

Decoded instructions may be issued to a given one of multiple executionunits. In the embodiment shown, these execution units include one ormore integer units 835, a multiply unit 840, a floating point/vectorunit 850, a branch unit 860, and a load/store unit 870. In anembodiment, floating point/vector unit 850 may be configured to handleSIMD or vector data of 128 or 256 bits. Still further, floatingpoint/vector execution unit 850 may perform IEEE-754 double precisionfloating-point operations. The results of these different executionunits may be provided to a writeback unit 880. Note that in someimplementations separate writeback units may be associated with each ofthe execution units. Furthermore, understand that while each of theunits and logic shown in FIG. 8 is represented at a high level, aparticular implementation may include more or different structures.

Note that in a processor having asymmetric cores, such as in accordancewith the micro-architectures of FIGS. 7 and 8, workloads may bedynamically swapped for power management reasons, as these cores,although having different pipeline designs and depths, may be of thesame or related ISA. Such dynamic core swapping may be performed in amanner transparent to a user application (and possibly kernel also).

A processor designed using one or more cores having pipelines as in anyone or more of FIGS. 5-8 may be implemented in many different endproducts, extending from mobile devices to server systems. Referring nowto FIG. 9, shown is a block diagram of a processor in accordance withanother embodiment of the present invention. In the embodiment of FIG.9, processor 900 may be a SoC including multiple domains, each of whichmay be controlled to operate at an independent operating voltage andoperating frequency. As a specific illustrative example, processor 900may be an Intel® Architecture Core™-based processor such as an i3, i5,i7 or another such processor available from Intel Corporation. However,other low power processors such as available from Advanced MicroDevices, Inc. (AMD) of Sunnyvale, Calif., an ARM-based design from ARMHoldings, Ltd. or licensee thereof or a MIPS-based design from MIPSTechnologies, Inc. of Sunnyvale, Calif., or their licensees or adoptersmay instead be present in other embodiments such as an Apple A7processor, a Qualcomm Snapdragon processor, or Texas Instruments OMAPprocessor. Such SoC may be used in a low power system such as asmartphone, tablet computer, phablet computer, Ultrabook™ computer orother portable computing device or connected device.

In the high level view shown in FIG. 9, processor 900 includes aplurality of core units 910 ₀-910 _(n). Each core unit may include oneor more processor cores, one or more cache memories and other circuitry.Each core unit 910 may support one or more instructions sets (e.g., anx86 instruction set (with some extensions that have been added withnewer versions); a MIPS instruction set; an ARM instruction set (withoptional additional extensions such as NEON)) or other instruction setor combinations thereof. Note that some of the core units may beheterogeneous resources (e.g., of a different design). In addition, eachsuch core may be coupled to a cache memory (not shown) which in anembodiment may be a shared level (L2) cache memory. A non-volatilestorage 930 may be used to store various program and other data. Forexample, this storage may be used to store at least portions ofmicrocode, boot information such as a BIOS, other system software or soforth.

Each core unit 910 may also include an interface such as a bus interfaceunit to enable interconnection to additional circuitry of the processor.In an embodiment, each core unit 910 couples to a coherent fabric thatmay act as a primary cache coherent on-die interconnect that in turncouples to a memory controller 935. In turn, memory controller 935controls communications with a memory such as a DRAM (not shown for easeof illustration in FIG. 9).

In addition to core units, additional processing engines are presentwithin the processor, including at least one graphics unit 920 which mayinclude one or more graphics processing units (GPUs) to perform graphicsprocessing as well as to possibly execute general purpose operations onthe graphics processor (so-called GPGPU operation). In addition, atleast one image signal processor 925 may be present. Signal processor925 may be configured to process incoming image data received from oneor more capture devices, either internal to the SoC or off-chip.

Other accelerators also may be present. In the illustration of FIG. 9, avideo coder 950 may perform coding operations including encoding anddecoding for video information, e.g., providing hardware accelerationsupport for high definition video content. A display controller 955further may be provided to accelerate display operations includingproviding support for internal and external displays of a system. Inaddition, a security processor 945 may be present to perform securityoperations such as secure boot operations, various cryptographyoperations and so forth.

Each of the units may have its power consumption controlled via a powermanager 940, which may include control logic to perform the variouspower management techniques described herein.

In some embodiments, SoC 900 may further include a non-coherent fabriccoupled to the coherent fabric to which various peripheral devices maycouple. One or more interfaces 960 a-960 d enable communication with oneor more off-chip devices. Such communications may be via a variety ofcommunication protocols such as PCIe™, GPIO, USB, I²C, UART, MIPI, SDIO,DDR, SPI, HDMI, among other types of communication protocols. Althoughshown at this high level in the embodiment of FIG. 9, understand thescope of the present invention is not limited in this regard.

Referring now to FIG. 10, shown is a block diagram of a representativeSoC. In the embodiment shown, SoC 1000 may be a multi-core SoCconfigured for low power operation to be optimized for incorporationinto a smartphone or other low power device such as a tablet computer orother portable computing device. As an example, SoC 1000 may beimplemented using asymmetric or different types of cores, such ascombinations of higher power and/or low power cores, e.g., out-of-ordercores and in-order cores. In different embodiments, these cores may bebased on an Intel® Architecture™ core design or an ARM architecturedesign. In yet other embodiments, a mix of Intel® and ARM cores may beimplemented in a given SoC.

As seen in FIG. 10, SoC 1000 includes a first core domain 1010 having aplurality of first cores 1012 ₀-1012 ₃. In an example, these cores maybe low power cores such as in-order cores. In one embodiment these firstcores may be implemented as ARM Cortex A53 cores. In turn, these corescouple to a cache memory 1015 of core domain 1010. In addition, SoC 1000includes a second core domain 1020. In the illustration of FIG. 10,second core domain 1020 has a plurality of second cores 1022 ₀-1022 ₃.In an example, these cores may be higher power-consuming cores thanfirst cores 1012. In an embodiment, the second cores may be out-of-ordercores, which may be implemented as ARM Cortex A57 cores. In turn, thesecores couple to a cache memory 1025 of core domain 1020. Note that whilethe example shown in FIG. 10 includes 4 cores in each domain, understandthat more or fewer cores may be present in a given domain in otherexamples.

With further reference to FIG. 10, a graphics domain 1030 also isprovided, which may include one or more graphics processing units (GPUs)configured to independently execute graphics workloads, e.g., providedby one or more cores of core domains 1010 and 1020. As an example, GPUdomain 1030 may be used to provide display support for a variety ofscreen sizes, in addition to providing graphics and display renderingoperations.

As seen, the various domains couple to a coherent interconnect 1040,which in an embodiment may be a cache coherent interconnect fabric thatin turn couples to an integrated memory controller 1050. Coherentinterconnect 1040 may include a shared cache memory, such as an L3cache, in some examples. In an embodiment, memory controller 1050 may bea direct memory controller to provide for multiple channels ofcommunication with an off-chip memory, such as multiple channels of aDRAM (not shown for ease of illustration in FIG. 10).

In different examples, the number of the core domains may vary. Forexample, for a low power SoC suitable for incorporation into a mobilecomputing device, a limited number of core domains such as shown in FIG.10 may be present. Still further, in such low power SoCs, core domain1020 including higher power cores may have fewer numbers of such cores.For example, in one implementation two cores 1022 may be provided toenable operation at reduced power consumption levels. In addition, thedifferent core domains may also be coupled to an interrupt controller toenable dynamic swapping of workloads between the different domains.

In yet other embodiments, a greater number of core domains, as well asadditional optional IP logic may be present, in that an SoC can bescaled to higher performance (and power) levels for incorporation intoother computing devices, such as desktops, servers, high performancecomputing systems, base stations forth. As one such example, 4 coredomains each having a given number of out-of-order cores may beprovided. Still further, in addition to optional GPU support (which asan example may take the form of a GPGPU), one or more accelerators toprovide optimized hardware support for particular functions (e.g. webserving, network processing, switching or so forth) also may beprovided. In addition, an input/output interface may be present tocouple such accelerators to off-chip components.

Referring now to FIG. 11, shown is a block diagram of another exampleSoC. In the embodiment of FIG. 11, SoC 1100 may include variouscircuitry to enable high performance for multimedia applications,communications and other functions. As such, SoC 1100 is suitable forincorporation into a wide variety of portable and other devices, such assmartphones, tablet computers, smart TVs and so forth. In the exampleshown, SoC 1100 includes a central processor unit (CPU) domain 1110. Inan embodiment, a plurality of individual processor cores may be presentin CPU domain 1110. As one example, CPU domain 1110 may be a quad coreprocessor having 4 multithreaded cores. Such processors may behomogeneous or heterogeneous processors, e.g., a mix of low power andhigh power processor cores.

In turn, a GPU domain 1120 is provided to perform advanced graphicsprocessing in one or more GPUs to handle graphics and compute APIs. ADSP unit 1130 may provide one or more low power DSPs for handlinglow-power multimedia applications such as music playback, audio/videoand so forth, in addition to advanced calculations that may occur duringexecution of multimedia instructions. In turn, a communication unit 1140may include various components to provide connectivity via variouswireless protocols, such as cellular communications (including 3G/4GLTE), wireless local area protocols such as Bluetooth™ IEEE 802.11, andso forth.

Still further, a multimedia processor 1150 may be used to performcapture and playback of high definition video and audio content,including processing of user gestures. A sensor unit 1160 may include aplurality of sensors and/or a sensor controller to interface to variousoff-chip sensors present in a given platform. An image signal processor1170 may be provided with one or more separate ISPs to perform imageprocessing with regard to captured content from one or more cameras of aplatform, including still and video cameras.

A display processor 1180 may provide support for connection to a highdefinition display of a given pixel density, including the ability towirelessly communicate content for playback on such display. Stillfurther, a location unit 1190 may include a GPS receiver with supportfor multiple GPS constellations to provide applications highly accuratepositioning information obtained using as such GPS receiver. Understandthat while shown with this particular set of components in the exampleof FIG. 11, many variations and alternatives are possible.

Referring now to FIG. 12, shown is a block diagram of an example systemwith which embodiments can be used. As seen, system 1200 may be asmartphone or other wireless communicator. A baseband processor 1205 isconfigured to perform various signal processing with regard tocommunication signals to be transmitted from or received by the system.In turn, baseband processor 1205 is coupled to an application processor1210, which may be a main CPU of the system to execute an OS and othersystem software, in addition to user applications such as manywell-known social media and multimedia apps. Application processor 1210may further be configured to perform a variety of other computingoperations for the device and perform the power management techniquesdescribed herein.

In turn, application processor 1210 can couple to a userinterface/display 1220, e.g., a touch screen display. In addition,application processor 1210 may couple to a memory system including anon-volatile memory, namely a flash memory 1230 and a system memory,namely a dynamic random access memory (DRAM) 1235. As further seen,application processor 1210 further couples to a capture device 1240 suchas one or more image capture devices that can record video and/or stillimages.

Still referring to FIG. 12, a universal integrated circuit card (UICC)1240 comprising a subscriber identity module and possibly a securestorage and cryptoprocessor is also coupled to application processor1210. System 1200 may further include a security processor 1250 that maycouple to application processor 1210. A plurality of sensors 1225 maycouple to application processor 1210 to enable input of a variety ofsensed information such as accelerometer and other environmentalinformation. An audio output device 1295 may provide an interface tooutput sound, e.g., in the form of voice communications, played orstreaming audio data and so forth.

As further illustrated, a near field communication (NFC) contactlessinterface 1260 is provided that communicates in a NFC near field via anNFC antenna 1265. While separate antennae are shown in FIG. 12,understand that in some implementations one antenna or a different setof antennae may be provided to enable various wireless functionality.

A PMIC 1215 couples to application processor 1210 to perform platformlevel power management. To this end, PMIC 1215 may issue powermanagement requests to application processor 1210 to enter certain lowpower states as desired. Furthermore, based on platform constraints,PMIC 1215 may also control the power level of other components of system1200.

To enable communications to be transmitted and received, variouscircuitry may be coupled between baseband processor 1205 and an antenna1290. Specifically, a radio frequency (RF) transceiver 1270 and awireless local area network (WLAN) transceiver 1275 may be present. Ingeneral, RF transceiver 1270 may be used to receive and transmitwireless data and calls according to a given wireless communicationprotocol such as 3G or 4G wireless communication protocol such as inaccordance with a code division multiple access (CDMA), global systemfor mobile communication (GSM), long term evolution (LTE) or otherprotocol. In addition a GPS sensor 1280 may be present. Other wirelesscommunications such as receipt or transmission of radio signals, e.g.,AM/FM and other signals may also be provided. In addition, via WLANtransceiver 1275, local wireless communications can also be realized.

Referring now to FIG. 13, shown is a block diagram of another examplesystem with which embodiments may be used. In the illustration of FIG.13, system 1300 may be mobile low-power system such as a tabletcomputer, 2:1 tablet, phablet or other convertible or standalone tabletsystem. As illustrated, a SoC 1310 is present and may be configured tooperate as an application processor for the device and perform the powermanagement techniques described herein.

A variety of devices may couple to SoC 1310. In the illustration shown,a memory subsystem includes a flash memory 1340 and a DRAM 1345 coupledto SoC 1310. In addition, a touch panel 1320 is coupled to the SoC 1310to provide display capability and user input via touch, includingprovision of a virtual keyboard on a display of touch panel 1320. Toprovide wired network connectivity, SoC 1310 couples to an Ethernetinterface 1330. A peripheral hub 1325 is coupled to SoC 1310 to enableinterfacing with various peripheral devices, such as may be coupled tosystem 1300 by any of various ports or other connectors.

In addition to internal power management circuitry and functionalitywithin SoC 1310, a PMIC 1380 is coupled to SoC 1310 to provideplatform-based power management, e.g., based on whether the system ispowered by a battery 1390 or AC power via an AC adapter 1395. Inaddition to this power source-based power management, PMIC 1380 mayfurther perform platform power management activities based onenvironmental and usage conditions. Still further, PMIC 1380 maycommunicate control and status information to SoC 1310 to cause variouspower management actions within SoC 1310.

Still referring to FIG. 13, to provide for wireless capabilities, a WLANunit 1350 is coupled to SoC 1310 and in turn to an antenna 1355. Invarious implementations, WLAN unit 1350 may provide for communicationaccording to one or more wireless protocols.

As further illustrated, a plurality of sensors 1360 may couple to SoC1310. These sensors may include various accelerometer, environmental andother sensors, including user gesture sensors. Finally, an audio codec1365 is coupled to SoC 1310 to provide an interface to an audio outputdevice 1370. Of course understand that while shown with this particularimplementation in FIG. 13, many variations and alternatives arepossible.

Referring now to FIG. 14, shown is a block diagram of a representativecomputer system such as notebook, Ultrabook™ or other small form factorsystem. A processor 1410, in one embodiment, includes a microprocessor,multi-core processor, multithreaded processor, an ultra low voltageprocessor, an embedded processor, or other known processing element. Inthe illustrated implementation, processor 1410 acts as a main processingunit and central hub for communication with many of the variouscomponents of the system 1400. As one example, processor 1400 isimplemented as a SoC.

Processor 1410, in one embodiment, communicates with a system memory1415. As an illustrative example, the system memory 1415 is implementedvia multiple memory devices or modules to provide for a given amount ofsystem memory.

To provide for persistent storage of information such as data,applications, one or more operating systems and so forth, a mass storage1420 may also couple to processor 1410. In various embodiments, toenable a thinner and lighter system design as well as to improve systemresponsiveness, this mass storage may be implemented via a SSD or themass storage may primarily be implemented using a hard disk drive (HDD)with a smaller amount of SSD storage to act as a SSD cache to enablenon-volatile storage of context state and other such information duringpower down events so that a fast power up can occur on re-initiation ofsystem activities. Also shown in FIG. 14, a flash device 1422 may becoupled to processor 1410, e.g., via a serial peripheral interface(SPI). This flash device may provide for non-volatile storage of systemsoftware, including a basic input/output software (BIOS) as well asother firmware of the system.

Various input/output (I/O) devices may be present within system 1400.Specifically shown in the embodiment of FIG. 14 is a display 1424 whichmay be a high definition LCD or LED panel that further provides for atouch screen 1425. In one embodiment, display 1424 may be coupled toprocessor 1410 via a display interconnect that can be implemented as ahigh performance graphics interconnect. Touch screen 1425 may be coupledto processor 1410 via another interconnect, which in an embodiment canbe an I²C interconnect. As further shown in FIG. 14, in addition totouch screen 1425, user input by way of touch can also occur via a touchpad 1430 which may be configured within the chassis and may also becoupled to the same I²C interconnect as touch screen 1425.

For perceptual computing and other purposes, various sensors may bepresent within the system and may be coupled to processor 1410 indifferent manners. Certain inertial and environmental sensors may coupleto processor 1410 through a sensor hub 1440, e.g., via an I_(2C)interconnect. In the embodiment shown in FIG. 14, these sensors mayinclude an accelerometer 1441, an ambient light sensor (ALS) 1442, acompass 1443 and a gyroscope 1444. Other environmental sensors mayinclude one or more thermal sensors 1446 which in some embodimentscouple to processor 1410 via a system management bus (SMBus) bus.

Also seen in FIG. 14, various peripheral devices may couple to processor1410 via a low pin count (LPC) interconnect. In the embodiment shown,various components can be coupled through an embedded controller 1435.Such components can include a keyboard 1436 (e.g., coupled via a PS2interface), a fan 1437, and a thermal sensor 1439. In some embodiments,touch pad 1430 may also couple to EC 1435 via a PS2 interface. Inaddition, a security processor such as a trusted platform module (TPM)1438 may also couple to processor 1410 via this LPC interconnect.

System 1400 can communicate with external devices in a variety ofmanners, including wirelessly. In the embodiment shown in FIG. 14,various wireless modules, each of which can correspond to a radioconfigured for a particular wireless communication protocol, arepresent. One manner for wireless communication in a short range such asa near field may be via a NFC unit 1445 which may communicate, in oneembodiment with processor 1410 via an SMBus. Note that via this NFC unit1445, devices in close proximity to each other can communicate.

As further seen in FIG. 14, additional wireless units can include othershort range wireless engines including a WLAN unit 1450 and a Bluetoothunit 1452. Using WLAN unit 1450, Wi-Fi™ communications can be realized,while via Bluetooth unit 1452, short range Bluetooth™ communications canoccur. These units may communicate with processor 1410 via a given link.

In addition, wireless wide area communications, e.g., according to acellular or other wireless wide area protocol, can occur via a WWAN unit1456 which in turn may couple to a subscriber identity module (SIM)1457. In addition, to enable receipt and use of location information, aGPS module 1455 may also be present. Note that in the embodiment shownin FIG. 14, WWAN unit 1456 and an integrated capture device such as acamera module 1454 may communicate via a given link.

An integrated camera module 1454 can be incorporated in the lid. Toprovide for audio inputs and outputs, an audio processor can beimplemented via a digital signal processor (DSP) 1460, which may coupleto processor 1410 via a high definition audio (HDA) link. Similarly, DSP1460 may communicate with an integrated coder/decoder (CODEC) andamplifier 1462 that in turn may couple to output speakers 1463 which maybe implemented within the chassis. Similarly, amplifier and CODEC 1462can be coupled to receive audio inputs from a microphone 1465 which inan embodiment can be implemented via dual array microphones (such as adigital microphone array) to provide for high quality audio inputs toenable voice-activated control of various operations within the system.Note also that audio outputs can be provided from amplifier/CODEC 1462to a headphone jack 1464. Although shown with these particularcomponents in the embodiment of FIG. 14, understand the scope of thepresent invention is not limited in this regard.

Embodiments may be implemented in many different system types. Referringnow to FIG. 15, shown is a block diagram of a system in accordance withan embodiment of the present invention. As shown in FIG. 15,multiprocessor system 1500 is a point-to-point interconnect system, andincludes a first processor 1570 and a second processor 1580 coupled viaa point-to-point interconnect 1550. As shown in FIG. 15, each ofprocessors 1570 and 1580 may be multicore processors, including firstand second processor cores (i.e., processors 1574 a and 1574 b andprocessor cores 1584 a and 1584 b), although potentially many more coresmay be present in the processors. In addition, each of processors 1570and 1580 also may include a graphics processor unit (GPU) 1573, 1583 toperform graphics operations. Each of the processors can include a PCU1575, 1585 to perform processor-based power management. In theembodiment of FIG. 15, processors 1570, 1580 may include MEP controllers1579, 1589, adapted separately from PCUs 1575, 1585, to performMEP-based determinations and provide initial and updated MEP values tothe corresponding PCUs, to enable the PCU to enhance its functionalityto perform energy control in addition to power control, as describedherein.

Still referring to FIG. 15, first processor 1570 further includes amemory controller hub (MCH) 1572 and point-to-point (P-P) interfaces1576 and 1578. Similarly, second processor 1580 includes a MCH 1582 andP-P interfaces 1586 and 1588. As shown in FIG. 15, MCH's 1572 and 1582couple the processors to respective memories, namely a memory 1532 and amemory 1534, which may be portions of system memory (e.g., DRAM) locallyattached to the respective processors. First processor 1570 and secondprocessor 1580 may be coupled to a chipset 1590 via P-P interconnects1562 and 1564, respectively. As shown in FIG. 15, chipset 1590 includesP-P interfaces 1594 and 1598.

Furthermore, chipset 1590 includes an interface 1592 to couple chipset1590 with a high performance graphics engine 1538, by a P-P interconnect1539. In turn, chipset 1590 may be coupled to a first bus 1516 via aninterface 1596. As shown in FIG. 15, various input/output (I/O) devices1514 may be coupled to first bus 1516, along with a bus bridge 1518which couples first bus 1516 to a second bus 1520. Various devices maybe coupled to second bus 1520 including, for example, a keyboard/mouse1522, communication devices 1526 and a data storage unit 1528 such as adisk drive or other mass storage device which may include code 1530, inone embodiment. Further, an audio I/O 1524 may be coupled to second bus1520. Embodiments can be incorporated into other types of systemsincluding mobile devices such as a smart cellular telephone, tabletcomputer, netbook, Ultrabook™, or so forth.

FIG. 16 is a block diagram illustrating an IP core development system1600 that may be used to manufacture an integrated circuit to performoperations according to an embodiment. The IP core development system1600 may be used to generate modular, re-usable designs that can beincorporated into a larger design or used to construct an entireintegrated circuit (e.g., an SoC integrated circuit). A design facility1630 can generate a software simulation 1610 of an IP core design in ahigh level programming language (e.g., C/C++). The software simulation1610 can be used to design, test, and verify the behavior of the IPcore. A register transfer level (RTL) design can then be created orsynthesized from the simulation model. The RTL design 1615 is anabstraction of the behavior of the integrated circuit that models theflow of digital signals between hardware registers, including theassociated logic performed using the modeled digital signals. Inaddition to an RTL design 1615, lower-level designs at the logic levelor transistor level may also be created, designed, or synthesized. Thus,the particular details of the initial design and simulation may vary.

The RTL design 1615 or equivalent may be further synthesized by thedesign facility into a hardware model 1620, which may be in a hardwaredescription language (HDL), or some other representation of physicaldesign data. The HDL may be further simulated or tested to verify the IPcore design. The IP core design can be stored for delivery to a thirdparty fabrication facility 1665 using non-volatile memory 1640 (e.g.,hard disk, flash memory, or any non-volatile storage medium).Alternately, the IP core design may be transmitted (e.g., via theInternet) over a wired connection 1650 or wireless connection 1660. Thefabrication facility 1665 may then fabricate an integrated circuit thatis based at least in part on the IP core design. The fabricatedintegrated circuit can be configured to perform operations in accordancewith at least one embodiment described herein.

Referring now to FIG. 17, shown is a flow diagram of a method inaccordance with an embodiment of the present invention. Morespecifically, method 1700 of FIG. 17 is a method for determining optimalminimum energy points (MEPs) in a processor in accordance with anembodiment. As such, method 1700 may be performed by hardware circuitry,firmware, software and/or combinations thereof. For example, at leastportions of method 1700 may be performed by a MEP controller of aprocessor, such as may be implemented in a power controller of theprocessor.

As illustrated, method 1700 begins by performing a sweep of voltage andfrequency to identify an initial optimum voltage (block 1710). Suchoperation may occur initially upon a first initialization of theprocessor, e.g., when configured in a given computing platform, eitherduring manufacturing testing and/or in the field. More specifically,this optimum voltage may correspond to a minimum energy point for theprocessor, based upon this sweep of voltage and frequency. For example,a power controller may cause the processor to operate at a set ofdifferent operating points each having a given operating voltage andoperating frequency. Based on sensor information an energy calculation(e.g., an energy per operation value) can be obtained during operationat these different operating points, from which the MEP can beidentified. And within this MEP, an initial optimum voltage isidentified. Next, at block 1720, this initial optimum voltage may bestored in a configuration storage, e.g., present in a configurationregister of a power controller. Note that at this point, with an initialoptimum voltage and optimal frequency corresponding to a MEP, aprocessor may begin or continue normal operation.

Thus as further illustrated in FIG. 17, at block 1730 during such normaloperation, temperature tracking information and activity trackinginformation may be received in the MEP controller. In an embodiment,temperature tracking information may be based on thermal informationfrom a plurality of thermal sensors that may be adapted in theprocessor. And the activity tracking information may, in an embodiment,be based at least in part on activity counter information regardingvarious micro-architectural activities of the processor, includingbandwidth information, cache operation, instructions per cycleinformation, among many other types of micro-architectural activityinformation.

Still with reference to FIG. 17, it is determined whether a change ineither of these different types of tracking information exceeds acorresponding threshold (diamond 1740). If not, control passes back toblock 1730 where additional tracking information may be received, e.g.,for a next evaluation interval. Note that in different embodiments thisevaluation interval may be according to a given timer, e.g., operatingat a given clock rate. In other cases, this evaluation interval may beaccording to an event-based trigger, by an asynchronous change inoperating condition that exceeds a threshold.

In any event, if it is determined that a change in at least one of thesedifferent types of tracking information exceeds a given threshold,control passes to block 1750. At block 1750 the temperature trackinginformation and/or the activity tracking information (e.g., one or boththat exceeds a corresponding threshold) may be processed. For example,this tracking information may be encoded into a corresponding step valuebased at least in part on the level of the tracking information. Andfrom such step values, further processing may be performed to determinean optimal step value.

Next, control passes to block 1760 where a voltage-frequency table maybe accessed using the determined optimal step value. More specifically,based upon this optimal step value, a given entry of thevoltage-frequency table may be accessed to obtain an optimum minimumenergy point operating point. This MEP point may correspond to anoperating voltage and frequency for this new optimum MEP. While shownnot shown for ease of illustration in FIG. 17, understand that an updateto the configuration storage to store the new optimum voltage can occur.Still further, understand that the power controller may control theprocessor to operate at this new optimum MEP.

Still with reference to FIG. 17, next may be determined whether anage-related timer has expired (diamond 1770). Understand that thisage-related timer may correspond to a relatively long time duration,e.g., on the order of months, semi-annually, annually or so forth. Thisis so, as such a relatively long time duration may cause age-relateddeterioration of the processor, such that it is possible that theinitial optimum voltage is no longer the correct voltage correspondingto a minimum energy point. Stated another way, this relatively long timeduration is a process-sensitive time duration at which process-baseddegradation may occur. Thus if it is determined that such age-relatedtimer expires, control passes back to block 1710 discussed above, wherea full sweep may be performed. Otherwise, continued temperature andactivity tracking may occur beginning at block 1730. Understand whileshown at this high level in the embodiment of FIG. 17, many variationsand alternatives are possible.

Referring now to FIG. 18, shown is a flow diagram of a method inaccordance with another embodiment of the present invention. Morespecifically, method 1800 of FIG. 18 is more detailed method forperforming tracking to determine appropriate update to a MEP inaccordance with an embodiment of the present invention. As such, method1800 may be performed by hardware circuitry, firmware, software and/orcombinations thereof. For example, at least portions of method 1800 maybe performed by a MEP controller.

As illustrated, method 1800 begins by receiving temperature trackinginformation and activity tracking information (block 1810), such asdiscussed above. Next, control passes to block 1820 where this trackinginformation may be compared to prior values of the tracking information.For example, the temperature tracking information may be compared to animmediately previous value of the temperature tracking information. Orin other cases, a moving average may be maintained to reflect a historyof the tracking information (and to provide a filtering and/orhysteresis control technique). Similar options exist for the activitytracking information, and any other tracking information that may beused in particular embodiments. Note further that with history data,machine learning-based pattern matching algorithms may be used toanalysis the history data to identify appropriate MEP values.

Still with reference to FIG. 18, next at diamond 1830 it is determinedwhether the change in tracking information exceeds a given threshold.For example, a first threshold may be associated with the temperaturetracking information, such that if the change exceeds this threshold,the determination at diamond 1830 is positive for the temperaturetracking information. And similarly, a second threshold may beassociated with the activity tracking information, such that if thechange exceeds this threshold, the determination at diamond 1830 ispositive for the activity tracking information. If the change(s) aredetermined not to exceed any such threshold, no further operation occursfor this evaluation interval, and continued tracking is performed,beginning at block 1810.

With further reference to FIG. 18, instead if it is determined that achange in at least one of the values of the tracking information exceedsa threshold level, control passes to block 1840. At block 1840, thechange of the threshold-exceeding tracking information may be encoded.More specifically, this change in tracking information may be encodedinto a step value. In an embodiment, this step value may be determined,e.g., with reference to a lookup table, in which an entry having aparticular step value can be accessed using the amount of the change.For example, with regard to temperature, a temperature change ofapproximately 55° C. may be encoded into a step value of N equals 1.Similarly, an activity level change of, e.g., 2×, may map into a stepvalue change of M equals 1. Of course many other example encodings arepossible.

Still referring to FIG. 18, at block 1850 an optimal step value may becalculated based on these one more step values. In a particularembodiment, an addition operation may be performed between the stepvalues (e.g., N and M) to obtain the optimal step value.

At block 1860, a voltage-frequency table may be accessed using thedetermined optimal step value to obtain an optimum MEP operating point.Next at block 1870 at least one voltage regulator of the processor maybe controlled using the optimum MEP operating point. More specifically,the obtained operating voltage value can be provided to one or morevoltage regulators to cause them to operate to output an operatingvoltage at this optimal operating voltage level. Similarly, at block1880, at least one clock generator of the processor may be controlledusing the optimum MEP operating point. More specifically, the obtainedoperating frequency value can be provided to one or more clockgenerators to cause them to operate to output a clock signal at thisoptimal operating frequency level. Understand while shown at this highlevel in FIG. 18, many variations and alternatives are possible.

Referring now to FIG. 19, shown is a graphical illustration of energyconsumption with relation to operating voltage. For a given workload,there is an optimal operating voltage (V_(opt)) that corresponds to aMEP. As shown in FIG. 19, for different workloads, the energy consumedreaches a MEP at V_(opt), typically in the near-threshold voltage (NTV)region with 4-5× better energy efficiency as compared to higheroperation points. From either direction (along the X-axis) at otheroperating voltages for the same workload, increased energy occurs. Andas shown, V_(opt) for different workloads (representative workloadscurves are present at curves 1910, 1920, 1930 and 1940) can shift byhundreds of millivolts with workload activity as the processor cyclesthrough various sleep modes. In addition, MEP and Vopt can also changewith operating conditions (e.g., due to variations in process, voltageand temperature (PVT)). As such, embodiments may provide a measure ofMEP tracking and adjustment to reduce energy consumption, illustrated inFIG. 19 with increasing activity (as moving towards the left along theX-axis).

As described herein, to reach the MEP, a power controller causes one orvoltage regulators to generate an operating voltage at the determinedMEP level. In addition, the PMU further causes one or more clockgenerators to generate one or more clock signals at the correspondingdetermined operating frequency of the MEP. Over a typical workloadinterval, energy per operation (Eop) calculations may be computed asfollows:Eop=(Vin*Iin_avg)/Fmax=P/Fmax=P*T  (Equation 1)

where, Vin equals input voltage, Fmax equals maximum frequency,T=1/Fmax; and where, power (P)=Vin*Iin_avg, and Iin_avg is the averagecurrent consumed over the workload interval (T) and may be provided viacurrent telemetry.

In a sweep operation, which may be performed at initialization of aprocessor to determine an initial MEP, and very infrequently to updatethis MEP to account for aging of the processor, a series of operationsare performed. More specifically, Table 1 below illustrates a recursivesweep operation to determine an MEP. As shown, a MEP controller maycompute the Eop at a plurality of points using Equation [1] to determinean optimum voltage (V_(OPT)). This MEP curve traversal may take someundesirable length of time, since the V/F sweep can consume substantialtime due to repeated clock frequency and voltage change delays in anincremental manner.

TABLE 1 1. Start at a reference point (V1, F1) 2. Compute T1 = 1/F1(reciprocal computation) 3. Compute Eop at point 1 4. Move to point 2(V2, F2) 5. Compute T2 = 1/F2 (reciprocal computation) 6. Compute Eop atpoint 2 7. Compare Eop1 and Eop2 8. Take decision

As described above, embodiments may minimally perform this sweep-baseddetermination of MEP. Instead, after an initial MEP is determinedaccording to a sweep such as performed in accordance with Table 1 above,embodiments may implement a faster parametric, sensor-based approach torun-time MEP tracking across PVT and workload conditions, with eachvariable being an input model parameter M.

Referring now to FIG. 20, shown is a set of representative simulated MEPcurves for changes in workload activity. As seen, diagram 2000illustrates a difference in Vopt for different workloads. For example,for a given workload x, Vopt may be at approximately 0.3 volts for afirst workload curve 2020. For a 16× increase in workload, asillustrated at curve 2010, Vopt may be at 0.15 volts. And finally, for areduction in workload by 16×, Vopt may be at 0.5 volts, as shown incurve 2030. As seen, a workload-based switching activity factor (α) isthe single largest contributor to MEP optimum shift, with largeractivity moving towards lower MEP values (and vice versa). Inembodiments, powers of 2 can be used as activity steps, however anyother multiple can be used.

Referring now to FIG. 21, shown are example illustrations of change inMEP versus temperature (shown at diagram 2110) and change in MEP withregard to change in activity (illustrated at diagram 2120). As shown indiagram 2110, when varying die temperature and keeping all otherparameters constant, there is a positive slope, with the MEP voltageshifting higher with higher temperatures. In this example, there is arepresentative slope of 10 mV for each 11 degree Centigrade change. Ofcourse, understand that other slopes are possible. In general, increasedleakage from increased temperature can shift the MEP V_(OPT) to a higheroptimum value (and vice versa).

As shown in diagram 2120 with a log-scale (for the X-axis), there is anegative slope for increasing workload changes, such that higheractivity results in lower MEP V/F values. In this example, there is achange of 50 mV MEP voltage for approximately every 2.5× change inworkload induced vector switching activity. With these considerationsfrom FIG. 21, for a given process, V_(OPT) changes are deterministic,depending on the temperature (T) and activity factor (a). Morespecifically, it can be seen that V_(OPT) is proportional to(a*Temp+b*Alpha), where “a” and “b” slope parameters. Note that thesevalues may be characterized by pre-silicon and/or post-silicon data. Andas shown, the slopes a, b are in opposite directions (+ for a, minus (−)for b).

Referring now to FIG. 22, shown is a block diagram of a MEP controllerin accordance with an embodiment of the present invention. As shown inFIG. 22, controller 2200 may be implemented as a hardware circuit. Inone implementation, MEP controller 2200 may be implemented within apower controller of a processor, such as a PCU. In other embodimentsunderstand that the MEP controller may be implemented as a separatehardware circuit that provides output information in the form of a MEPperformance state (e.g., including an optimal operating voltage andoptimal operating frequency) to a power controller. In still otherembodiments, understand that the various constituent components of MEPcontroller 2200 may be distributed, with certain information beingprovided to MEP control circuitry and in turn additional informationbeing output to, e.g., a power controller.

As illustrated in FIG. 22, MEP controller 2200 includes aprocess-temperature tracker 2210. In embodiments, process-temperaturetracker 2210 may receive incoming thermal information, e.g., in the formof temperature values from one or more temperature sensors adaptedthroughout the processor. In an embodiment, temperature may bedetermined using a calibrated ring oscillator or similar circuitry.Process-temperature tracker 2210 may process the incoming thermalinformation to provide a temperature change (a change in temperature(δT). To this end, process-temperature tracker 2210 may maintaininformation regarding prior temperature information received to providethis change in temperature, which may be performed on an evaluationcycle-by-evaluation cycle basis. In other cases, tracker 2210 maymaintain a moving average to filter or smooth out instantaneousvariations. In any event, tracker 2210 outputs this change in thermaltracking information to a MEP controller 2240. In addition,process-temperature tracker 2210 may include a processor sensor whichmay be implemented using a ring oscillator to detect whether the siliconis of, e.g., a typical, slow or fast variation. Such sensor may providea reference to set an initial MEP value. More specifically, a MEPcontroller may use this process variation, along with voltage/frequencysweep information to determine the initial MEP value.

As further shown, MEP controller 2200 also includes an activity monitor2220. In some cases, note that activity monitor 2220 may receiveincoming microarchitectural monitoring information, e.g., from aperformance monitoring unit (PMU) of the processor. In an embodiment,activity factor estimation can be determined using micro-architecturaland performance counters for switching events occurring at instructionlevel, e.g., cache hits, cache miss, loads, fused multiply add (FMA)retires, instruction retires, etc. A measure of activity can be inferredfrom these counters. As such, it is possible for monitor 2220 to beimplemented in the PMU itself. Activity monitor 2220 may maintaininformation regarding prior activity information to provide this changein temperature, which may be performed on an evaluationcycle-by-evaluation cycle basis. In other cases, activity monitor 2220may maintain a moving average to filter or smooth out instantaneousvariations. In any event, activity monitor 2220 outputs this change inactivity tracking information to MEP controller 2240.

Note that process-temperature tracker 2210 and activity monitor 2220 mayoperate during runtime to provide information that may be used to adjustoptimal voltage during runtime based on workload and/or temperature ofthe processor. Thus in the embodiment of FIG. 22, trackers 2210, 2220may perform rapid V_(OPT) adjustment during run time, based on data fromprocess, temperature and activity monitors/sensors. Note that indifferent embodiments, the sensors and MEP controller can be on-die oroff-die.

Still further, understand that a sweeping-type MEP determination alsomay be performed, e.g., one time upon initialization of the processor.In addition, at process-sensitive time durations (which may be on theorder of months, years or so forth), this sweep operation may beperformed to determine an updated optimum MEP. As such as furtherillustrated in FIG. 22, a power management integrated circuit (PMIC)current telemetry circuit 2230 also may be present. Telemetry circuit2230 may be implemented within integrated voltage regulator circuitry ofthe processor. In other cases, telemetry circuit 2230 may be separatefrom such voltage regulator, but in either case receives current sensinginformation from the voltage regulator. Telemetry circuit 2230 mayprovide power data that can be used to compute energy (e.g., accordingto Equation 1 above) for one-time MEP tracking to obtain V_(OPT). Inother embodiments, this sweep tracking may be avoided where a priorvalue is preloaded. Based on this information, current telemetryinformation may be provided to MEP controller 2240.

In various embodiments, MEP controller 2240 may perform both acomputation of long-term MEPs, as well as real time adjustment to suchMEP values, using information from process-temperature tracker 2210 andactivity monitor 2220. As such, MEP control circuit 2240 may performcalculations based on the change in tracking information received fromprocess-temperature tracker 2210 and activity monitor 2220. Based on thecomputations, access to a lookup table 2245 may occur to determine anoptimal MEP performance state. This optimal MEP performance state may beoutput to power control circuitry to control operating voltage and/oroperating frequency of one or more cores or other processing circuits.Understand while shown at this high level in the embodiment of FIG. 22,many variations and alternatives are possible.

Referring now to FIG. 23, shown is a block diagram of a MEP controllerin accordance with another embodiment of the present invention. In theembodiment of FIG. 23, an environment 2300 is shown with further detailthat illustrates operations performed based on receipt of thermaltracking information and activity tracking information fromcorresponding process-temperature tracker 2310 and activity monitor2320.

As illustrated in FIG. 23, a MEP controller 2330 includes correspondingcomparator and threshold circuitry 2332, 2342 to receive the incomingchange in tracking information and compare it to correspondingthresholds, which in embodiments may be programmable thresholds. In anembodiment, MEP controller 2330 may periodically compare (and threshold)temperature and activity factor digital codes from correspondingsensors. When it is determined that the change in tracking informationexceeds the corresponding threshold, the change in tracking informationvalues (δT and δα) are provided to corresponding difference encoders2334, 2344. Encoders 2334, 2344 may encode maximum difference values(e.g., δT, δα) into discrete steps. In embodiments herein, thesedifference encoders may include or be coupled to one or more trackingtables to output a corresponding step value (n and/or m) based on thelevel of the change in tracking information. For example, in anembodiment one or more LUTs may be populated with a realistic range ofpre-characterized temperature change (δT) and workload shift (δα) data.In one embodiment, a linear model may be used with activity triggers forevery 2× change in workload and/or 55° C. change in temperature.

As further illustrated in FIG. 23, these step values are provided to acomputation circuit 2360, which may process these values to determine anoptimal step value. In one embodiment, computation circuit 2360 maycompute this optimal step value according to: δT−δα. More particularly,a sum operation may be performed on the step values corresponding to thetracking changes. In an embodiment, computation circuit 2360 may computea sum (or difference) of (δT−δα), based on the temperature and activitysensor data, and may be implemented as a low overhead digitaladder/subtraction circuit. Computation circuit 2360, in an embodiment,may also receive telemetry information from a voltage regulator, whichmay provide information regarding current consumption.

As further illustrated, MEP controller 2330 includes a lookup tablememory 2370, which includes a plurality of entries each including avoltage value and a frequency value. MEP controller 2330 may access agiven entry of memory 2370 using the optimal step value to output anoptimum MEP performance state (including an optimal operating voltageand an optimal operating frequency). In one particular example, for a+55° C., −4× activity change, values of δT=+1, δα=−2 may be generated,giving 1−(−2)=3 steps (2+steps from activity, and 1 positive step fromtemperature). Here, 50 mV=1 step, and 55° C. change=1 step. So the newV_(OPT) is 0.2V (an original value)+0.15 V, resulting in 0.35V. Notethat in an embodiment, the optimal step value may be converted into amemory address to access LUT 2370, which provides the final/optimal MEPpoint (V, F) setting to be used to set operating voltage and frequencyfor one or more domains of the processor.

In embodiments, MEP controller 2330 may provide this information to apower controller that in turn may control one or more voltage regulatorsand/or one or more clock generation circuits to output one or moreoperating voltages and/or one or more clock signals at the givenoperating frequency. Understand while shown at this high level in theembodiment of FIG. 23, many variations and alternatives are possible.

Embodiments thus may realize a dramatic reduction in computation andspeed by effectively using sensor data and heuristics to intelligentlyadjust the optimum MEP in a relative manner, as compared to an expensiveabsolute MEP tracking technique. Understand that while this example usestrigger steps of 50° C. and 2× workload changes, the extent of discretesteps/action may differ. And with embodiments, per-die and/orper-process skew silicon adjustments may be realized by way of LUTinformation determined during manufacture. In other cases, silicon-agingsensors may be used to obtain age-based deterioration information toautomatically adjust for long-term MEP shifts.

Table 2 below illustrates an example a pre-characterized lookup tablefor determining activity-based step changes. Understand that a similartable may be used for determining temperature-based changes, whereresulting step values can be summed as discussed above to obtain anoptimal step value that may be used to access a voltage-frequency table.

TABLE 2 Activity (δα) Temperature (δT) VoptStep 2x 110 −1 4x 110 −2 8x110 −3 16x  110 −4   0.5x 110 1   0.25x 110 2    0.125x 110 3    0.0625x110 4

With embodiments, dynamic computation of energy consumption isperformed, which is a more apt metric for extending battery life ascompared to conventional power monitoring-based techniques. Statedanother way, minimum power consumption modes do not necessarilytranslate into minimum energy modes. Embodiments thus providesensor-driven, fast real-time MEP tracking and re-locking, eliminatingthe need for slower voltage/frequency-based sweep techniques, with lowhardware cost. Note that in some cases, at least portions of theoperations performed by a MEP controller may be implemented within otherhardware, firmware and/or software, e.g., of a power controller.

The following examples pertain to further embodiments.

In one example, a processor comprises: at least one core to executeinstructions; at least one temperature sensor to output thermalinformation regarding the processor; an activity monitor to monitoractivity of the processor and to output activity information based atleast in part thereon; and a MEP controller coupled to the at least onetemperature sensor and the activity monitor. The MEP controller may beconfigured to: generate a change in thermal tracking information, basedat least in part on prior thermal information and the thermalinformation; generate a change in activity tracking information, basedat least in part on prior activity information and the activityinformation; and determine a MEP performance state based at least inpart on the change in thermal tracking information and the change inactivity tracking information.

In an example, the MEP controller comprises: an encoder to encode thechange in thermal tracking information into a first step value and anencoder to encode the change in activity tracking information into asecond step value; and a calculation circuit to compute a step valuebased on the first step value and the second step value.

In an example, the MEP controller further comprises a control circuit tooutput a MEP performance state based on the step value.

In an example, the processor further comprises a lookup table comprisinga plurality of entries each to store an operating voltage and anoperating frequency, where the control circuit is to access the lookuptable using the step value.

In an example, the calculation circuit is to sum the first step valueand the second step value to compute the step value.

In an example, the processor further comprises at least one trackingtable including a plurality of entries each to associate the change inthermal tracking information with a corresponding first step value.

In an example, the encoder is to access the at least one tracking tablewith the change in thermal tracking information to obtain the first stepvalue.

In an example, the at least one tracking table comprisespre-characterized temperature change data.

In an example, the processor further comprises a power controllercoupled to the MEP controller, the power controller to cause a voltageregulator to output a first operating voltage according to the MEPperformance state and to cause a clock generation circuit to output aclock signal at a first operating frequency according to the MEPperformance state.

In an example, the MEP controller further comprises a sweep circuit totrigger a sweep of voltage/frequency values to determine an optimum MEPperformance state, the sweep circuit to trigger the sweep in response toexpiration of an aging timer to indicate expiration of aprocess-sensitive time duration.

In an example, the sweep circuit is further to trigger the sweep ofvoltage/frequency values to determine an initial optimum MEP performancestate upon initialization of the processor.

In an example, the processor further comprises a configuration storageto store at least an optimal voltage of the initial optimum MEPperformance state.

In an example, the MEP controller is to prevent update to the MEPperformance state if the change in thermal tracking information and thechange in activity tracking information are less than a correspondingthreshold.

In another example, a method comprises: receiving, in a MEP controllerof a processor, thermal tracking information regarding a temperature ofthe processor and activity tracking information regarding activity ofthe processor; generating a change in tracking information, based atleast in part on the thermal tracking information and the activitytracking information; computing a step value based at least in part onthe change in tracking information; and outputting a MEP performancestate using the step value.

In an example, the method further comprises determining a processvariation and sweeping a plurality of voltage/frequency values todetermine an initial optimum MEP performance state upon initializationof the processor.

In an example, the method further comprises determining a processvariation and sweeping the plurality of voltage/frequency values todetermine an updated optimum MEP performance state, in response toexpiration of a process-sensitive time duration.

In an example, the method further comprises: accessing a lookup tablecomprising a plurality of entries each to store an operating voltage andan operating frequency using the step value to obtain the MEPperformance state; and accessing at least one tracking with the changein tracking information to obtain one or more step values used tocompute the step value.

In another example, a computer readable medium including instructions isto perform the method of any of the above examples.

In a further example, a computer readable medium including data is to beused by at least one machine to fabricate at least one integratedcircuit to perform the method of any one of the above examples.

In a still further example, an apparatus comprises means for performingthe method of any one of the above examples.

In another example, a system includes a processor comprising: aplurality of cores: at least one sensor to output thermal informationregarding the processor; at least one process sensor to output processvariation information regarding the processor; an activity monitor tomonitor activity of the processor and to output activity informationbased at least in part thereon; and a MEP controller coupled to the atleast one sensor, the at least one process sensor and the activitymonitor. The MEP controller may be configured to determine an initialMEP operating point based on a sweep of voltage/frequency values and theprocess variation information, and thereafter to adjust the initial MEPoperating point to an updated MEP operating point based at least in parton the thermal information and the activity information and without thesweep of voltage/frequency values. The system may further include adynamic random access memory coupled to the processor.

In an example, the MEP controller is to: generate a change in thermaltracking information, based at least in part on prior thermalinformation and the thermal information; generate a change in activitytracking information, based at least in part on prior activityinformation and the activity information; and determine the updated MEPoperating point based at least in part on the change in thermal trackinginformation and the change in activity tracking information.

In an example, the MEP controller comprises: an encoder to encode thechange in thermal tracking information into a first step value and anencoder to encode the change in activity tracking information into asecond step value; and a calculation circuit to compute a step valuebased on the first step value and the second step value, and where theMEP controller is to determine the updated MEP operating point based onthe step value.

Understand that various combinations of the above examples are possible.

Note that the terms “circuit” and “circuitry” are used interchangeablyherein. As used herein, these terms and the term “logic” are used torefer to alone or in any combination, analog circuitry, digitalcircuitry, hard wired circuitry, programmable circuitry, processorcircuitry, microcontroller circuitry, hardware logic circuitry, statemachine circuitry and/or any other type of physical hardware component.Embodiments may be used in many different types of systems. For example,in one embodiment a communication device can be arranged to perform thevarious methods and techniques described herein. Of course, the scope ofthe present invention is not limited to a communication device, andinstead other embodiments can be directed to other types of apparatusfor processing instructions, or one or more machine readable mediaincluding instructions that in response to being executed on a computingdevice, cause the device to carry out one or more of the methods andtechniques described herein.

Embodiments may be implemented in code and may be stored on anon-transitory storage medium having stored thereon instructions whichcan be used to program a system to perform the instructions. Embodimentsalso may be implemented in data and may be stored on a non-transitorystorage medium, which if used by at least one machine, causes the atleast one machine to fabricate at least one integrated circuit toperform one or more operations. Still further embodiments may beimplemented in a computer readable storage medium including informationthat, when manufactured into a SoC or other processor, is to configurethe SoC or other processor to perform one or more operations. Thestorage medium may include, but is not limited to, any type of diskincluding floppy disks, optical disks, solid state drives (SSDs),compact disk read-only memories (CD-ROMs), compact disk rewritables(CD-RWs), and magneto-optical disks, semiconductor devices such asread-only memories (ROMs), random access memories (RAMs) such as dynamicrandom access memories (DRAMs), static random access memories (SRAMs),erasable programmable read-only memories (EPROMs), flash memories,electrically erasable programmable read-only memories (EEPROMs),magnetic or optical cards, or any other type of media suitable forstoring electronic instructions.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thetrue spirit and scope of this present invention.

What is claimed is:
 1. A processor comprising: at least one core toexecute instructions; at least one temperature sensor to output thermalinformation regarding the processor; an activity monitor to monitoractivity of the processor and to output activity information based atleast in part thereon; and a minimum energy point (MEP) controllercoupled to the at least one temperature sensor and the activity monitor,the MEP controller to: generate a change in thermal trackinginformation, based at least in part on prior thermal information and thethermal information; generate a change in activity tracking information,based at least in part on prior activity information and the activityinformation; and determine a MEP performance state based at least inpart on the change in thermal tracking information and the change inactivity tracking information.
 2. The processor of claim 1, wherein theMEP controller comprises: an encoder to encode the change in thermaltracking information into a first step value and an encoder to encodethe change in activity tracking information into a second step value;and a calculation circuit to compute a step value based on the firststep value and the second step value.
 3. The processor of claim 2,wherein the MEP controller further comprises a control circuit to outputthe MEP performance state based on the step value.
 4. The processor ofclaim 3, further comprising a lookup table comprising a plurality ofentries each to store an operating voltage and an operating frequency,wherein the control circuit is to access the lookup table using the stepvalue.
 5. The processor of claim 3, wherein the calculation circuit isto sum the first step value and the second step value to compute thestep value.
 6. The processor of claim 2, further comprising at least onetracking table including a plurality of entries each to associate thechange in thermal tracking information with a corresponding first stepvalue.
 7. The processor of claim 6, wherein the encoder is to access theat least one tracking table with the change in thermal trackinginformation to obtain the first step value.
 8. The processor of claim 7,wherein the at least one tracking table comprises pre-characterizedtemperature change data.
 9. The processor of claim 1, further comprisinga power controller coupled to the MEP controller, the power controllerto cause a voltage regulator to output a first operating voltageaccording to the MEP performance state and to cause a clock generationcircuit to output a clock signal at a first operating frequencyaccording to the MEP performance state.
 10. The processor of claim 1,wherein the MEP controller further comprises a sweep circuit to triggera sweep of voltage/frequency values to determine an optimum MEPperformance state, the sweep circuit to trigger the sweep in response toexpiration of an aging timer to indicate expiration of aprocess-sensitive time duration.
 11. The processor of claim 10, whereinthe sweep circuit is further to trigger the sweep of voltage/frequencyvalues to determine an initial optimum MEP performance state uponinitialization of the processor.
 12. The processor of claim 11, furthercomprising a configuration storage to store at least an optimal voltageof the initial optimum MEP performance state.
 13. The processor of claim1, wherein the MEP controller is to prevent update to the MEPperformance state if the change in thermal tracking information and thechange in activity tracking information are less than a correspondingthreshold.
 14. A non-transitory machine-readable medium having storedthereon instructions, which if performed by a machine cause the machineto perform a method comprising: receiving, in a minimum energy point(MEP) controller of a processor, thermal tracking information regardinga temperature of the processor and activity tracking informationregarding activity of the processor; generating a change in trackinginformation, based at least in part on the thermal tracking informationand the activity tracking information; computing a step value based atleast in part on the change in tracking information; and outputting aMEP performance state using the step value.
 15. The non-transitorymachine-readable medium of claim 14, wherein the method furthercomprises determining a process variation of the processor and sweepinga plurality of voltage/frequency values to determine an initial optimumMEP performance state upon initialization of the processor.
 16. Thenon-transitory machine-readable medium of claim 15, wherein the methodfurther comprises sweeping the plurality of voltage/frequency values todetermine an updated optimum MEP performance state, in response toexpiration of a process-sensitive time duration.
 17. The non-transitorymachine-readable medium of claim 14, wherein the method furthercomprises: accessing a lookup table comprising a plurality of entrieseach to store an operating voltage and an operating frequency using thestep value to obtain the MEP performance state; and accessing at leastone tracking table with the change in tracking information to obtain oneor more step values used to compute the step value.
 18. A systemcomprising: a processor comprising: a plurality of cores; at least onesensor to output thermal information regarding the processor; at leastone process sensor to output process variation information regarding theprocessor; an activity monitor to monitor activity of the processor andto output activity information based at least in part thereon; and aminimum energy point (MEP) controller coupled to the at least onesensor, the at least one process sensor and the activity monitor,wherein the MEP controller is to determine an initial MEP operatingpoint based on a sweep of voltage/frequency values and the processvariation information, and thereafter to adjust the initial MEPoperating point to an updated MEP operating point based at least in parton the thermal information and the activity information and without thesweep of voltage/frequency values; and a dynamic random access memorycoupled to the processor.
 19. The system of claim 18, wherein the MEPcontroller is to: generate a change in thermal tracking information,based at least in part on prior thermal information and the thermalinformation; generate a change in activity tracking information, basedat least in part on prior activity information and the activityinformation; and determine the updated MEP operating point based atleast in part on the change in thermal tracking information and thechange in activity tracking information.
 20. The system of claim 19,wherein the MEP controller comprises: an encoder to encode the change inthermal tracking information into a first step value and an encoder toencode the change in activity tracking information into a second stepvalue; and a calculation circuit to compute a step value based on thefirst step value and the second step value, and wherein the MEPcontroller is to determine the updated MEP operating point based on thestep value.